Microstructure and microwave absorption properties of Fe3O4/dextran/SnO2 multilayer microspheres

Fe3O4/dextran/SnO2 multilayer microspheres have been successfully designed and synthesized by solvothermal and hydrothermal reactions. Dextran worked as a linker between Fe3O4 core and SnO2 shell. It can not only prevent the oxidation of Fe3O4 but also be carbonize to another absorber carbon black. The as-synthesized microspheres were about 320 nm in size and well-defined in shape. The maximum reflection loss of Fe3O4/dextran/SnO2 microspheres and paraffin wax composites could reach 20.26 dB at 4.72 GHz, and the bandwidth with a reflection loss less than − 10 dB was 4.86 GHz with 4 mm in thickness. The excellent microwave absorption properties of the composites were attributed to the special multilayer structures of Fe3O4/dextran/SnO2 microspheres and the effective complementarity between dielectric loss and magnetic loss.

► Fe3O4/dextran/SnO2 multilayer microspheres were designed as microwave absorber.
► Synthesis combined the solvothermal and hydrothermal reactions.
► Multilayer structure and effective complementarities between the dielectric loss and magnetic loss enhanced microwave absorption properties.